Brakes

I just brought my first Audi three month ago, a '88 90 and I love it.
This car has 103550 miles on it when I bought it, the body and interior
condition was great, it looks beautiful. Since I brought the car I had the
trans. and motor mounts replaced and the transmission flushe-Cost me
$600. A month ago I've notice a grinding sound coming from my right front
wheel...I assume it might be a loose caliper or the bearings. But after
driving the car for another two weeks the sound went away. But now
sometime when I brake hard the brake makes thumping sounds and yesterday
my speedometer stoped working. Could the brake noise and the speedometer
resulted from me not taking care of the griding sound a month
ago? I'm a college student and I can't afford to spend too much on
fixing the car. Before I take my car to the garage does anyone know how
much it my cost to replace the caliper or bearing. Or is my problem more
than just the caliper or bearing that I assumed? HELP!!!!!!!